<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Size</title>
<style type="text/css">
div {
    width: 800px;
    height: 500px;
    background-image: url('bg2.png'), url('bg1.jpg');
    background-image: url('bg1.jpg'), url('bg2.png');
}
</style>
</head>
<body>
<div></div>
</body>
</html>